1. Field of the Invention
The present invention relates to a method for producing a cylinder having scavenging passages for two-cycle internal combustion engine.
2. The Prior Art
In a cylinder having scavenging passages for a two-cycle internal combustion engine, scavenging passages are formed in a peripheral wall of the cylinder for feeding scavenging mixture precompressed within a crank case into the cylinder. In general, the scavenging passages are formed integrally in a C-shaped crosssection in the longitudinal or axial direction in a wall of the cylinder. Conventionally, such a cylinder has been produced by using a gravity casting method or a low pressure casing method by using a lost core. It has been impossible to produce such a cylinder through a high pressure die-casting method. Also, in the case where the cylinder should be formed through the high pressure die-casting method, it is necessary to use a metal bore core that has an intricate split die configuration. As a result, the manufacturing cost for the cylinder would be increased, and the manufacturing efficiency would be low.